Door impact beams are reinforcing members located within the side doors of automotive vehicles. Their primary purpose is to enhance the impact resistance of the side doors, thereby helping to preserve the general integrity of the automobile in the event of a collision of an object with the broadside of the automobile. The impact beams are located within the door and extend along the length of the door. The ends of the beams are often secured to mounting fixtures which connect the beams to a supporting structure within the door. The beam and its mounting fixtures together constitute the beam assembly.
Impact beams have been made in a variety of cross-sectional shapes, as evidenced by U.S. Pat. No. 4,090,734, issued May 23, 1978 to S. Inami et al., U.S. Pat. No. 4,684,166, issued Aug. 4, 1987 to V. L. Kanodia, and U.S. Pat. No. 4,978,562, issued Dec. 18, 1990 to J. S. Wycech. As shown in the latter of these patents, the impact beam can have a tubular conformation.
In some instances one or both end portions of the impact beam are formed to have a reduced profile. This has been done to provide an appropriately shaped surface to secure the impact beam to the supporting structure within the door. See, for example, U.S. Pat. No. 5,080,427, issued Jan. 24, 1992 to P. Sturrus et al., as well as the aforementioned patent to Wycech. Alternatively, this is sometimes done because the clearance provided within the door for the ends of the impact beam assembly (i.e., the mounting fixtures and end portions of the impact beam) is not enough to accept the full width of the beam. In these instances, the profile of the end portions of the impact beams must be reduced to match the clearance provided.
One way in which the profile of the end portions of the impact beams have been reduced is to remove material, whether by cutting, grinding, or some other means. See, for example, U.S. Pat. No. 4,708,390, issued Nov. 24, 1987 to G. H. Palentyn et al., U.S. Pat. No. 5,118,159, issued Jun. 2, 1992 to T. J. Horling et al., and U.S. Pat. No. 5,123,694, issued Jun. 23, 1992 to R. J. DePierre et al. A second way has been to flatten part or all of the end portion of the impact beam.
One problem associated with reducing the profile of the impact beams at their end portions is that the overall strength and, particularly important, the tensile strength of the impact beam may be reduced. Also, extreme deformation of the end portions can result in cracking of the impact beam under the vibratory conditions to which the impact beam may be exposed, thereby further reducing the strength of the impact beam. Thus, it would be desirable to have an impact beam assembly construction that provides an end portion having a reduced profile with sufficient structural integrity such that the beam assembly remains suitable for its intended purpose.